Novel vitamin E forms in leaves of Kalanchoe daigremontiana and Phaseolus coccineus

In the present study, we isolated novel tocochromanols from green leaves of Kalanchoe daigremontiana and primary leaves of etiolated seedlings of Phaseolus coccineus that were identified as beta-, gamma-, and delta-tocomonoenols with unsaturation at the terminal isoprene unit of the side chain. The content of gamma-tocomonoeno in leaves of etiolated bean increased gradually with the age of seedlings, reaching 50% of the gamma-tocopherol level in 40-day-old plants. The content of this compound in leaves was increased by short illumination of etiolated plants and by addition of homogentisic acid, a biosynthetic precursor of tocopherols. These data indicated that gamma-tocomonoenol is synthesized de novo from homogentisic acid and tetrahydro-geranylgeraniol diphosphate, a phytol precursor. Based on these results, a biosynthetic pathway of tocomonoenols is proposed. (C) 2011 Elsevier GmbH. All rights reserved.